This invention relates to a method and apparatus for retaining closure of shells of bi-valve mollusks in preparation for high pressure processing. More particularly, the invention relates to a method of preventing escape of natural juices from the shells of molluskan shellfish, such as oysters, clams and the like.
It has been discovered that application of high pressure and heat to raw molluscan shellfish, more specifically to bi-valve mollusks, tends to release adductor muscle of the mollusks and allow easy opening of the shells for extracting the mollusk from the shell. This phenomenon is described in more detail in my co-pending applications relating to shucking of molluskan shellfish with the use of high pressure processing.
Opening of the shell during high-pressure processing may be desirable under certain circumstances. However, in some cases it is also important to prevent escape of natural juices from the shell during high-pressure processing. For instance, many restaurants arid oyster bars that serve raw shellfish on a half-shell prefer that the oysters arrive in their natural state, with the juices intact within their shell. Retention of juices, additionally, allows preserving the natural state of the shellfish and retaining sensory qualities of the product. It was discovered that banding of shelled shellfish prior to high pressure processing helps retain the shell halves closed and retain natural juices inside the shells.
One of the known shellfish banding processes is disclosed in U.S. Pat. No. 5,773,064 issued on Jun. 30, 1998 to Tesvich, et al. entitled xe2x80x9cHeat Treatment of Raw Moleskin Shellfish Including a Banding Process.xe2x80x9d In that patent, a band is secured about the two halves of a molluskan shell, such as oyster. The band may be elastic, plastic, metal, heat-shrinkable material and is said to be applied about the mollusk by a conventional banding machine. The preferred band of the ""064 patent is an elastic or rubber band. After banding, the mollusk is exposed to heat treatment in a fluid bath at a temperature of about 110 to 140 degrees Fahrenheit.
Another example of shellfish banding is disclosed in Japanese application No. 60049770A, published on Mar. 19, 1985. In the Japanese reference, it is suggested to bind a heat-resistant band about an unshelled shellfish and then seal the shellfish in a heat resistant plastic packaging.
While these patent documents suggest banding of shellfish, they do not disclose in any particular detail the method of applying the band or any apparatus for achieving this goal. The present invention contemplates provision of a method of retaining closure of shellfish during high pressure processing and an apparatus therefor.
It is, therefore, an object of the present invention to provide a method of retaining closure of shelled bivalve molluscan shellfish in preparation for high pressure processing.
It is another object of the present invention to provide an apparatus for use with the method of retaining closure of shelled bivalve mollusks in preparation to high-pressure treatment.
It is a further object of the present invention to provide an apparatus for use with the method of retaining closure of bi-valve mollusks by banding.
These and other objects of the present invention are achieved through a provision of a method and apparatus of banding raw shelled molluscan shellfish in preparation to high-pressure processing. Shelled product is placed on a conveyor belt that is divided into a plurality of compartments. Heat-shrink bands are wrapped around each shell. As the conveyor moves, the product is exposed to elevated temperature of about 300-400 degrees Fahrenheit for 2-3 seconds. Heat causes the band to shrink and tightly adhere around each shell.
To prevent denaturing of the product, moving the product on conveyor belt to the next station, which is a cool-down station, then immediately arrests heating process. The product is exposed to a stream of cold air of about 30 degrees Fahrenheit for about 1 second. Then, the conveyor moves the product downstream, where the product is deposited by gravity into a receiving container, which is placed below the end of the conveyor.
The conveyor belt is made of flexible, resilient slightly stretchable material. The conveyor is divided into a plurality of compartments by outwardly extending flexible separating members. When the belt moves around feed rollers, the outer surface of the conveyor belt stretches, and the shellfish is placed into the compartments. As the belt moves, it returns to its non-stretched condition, which causes the separating members, or fins to come closer together and secure the shelled product in the compartments.
As the conveyor belt moves around the downstream feed roller, the belt stretches again and the shells fall out of the compartments into the receiving container.
The method and apparatus of the present invention allow significantly expediting the banding process and reducing the labor costs. Additionally, uniform application of heat and cool air reduces the human-error factor, thereby preventing waste of the product.